Ascending aortic dilatation evaluated by 4D PC-MRI was associated with increased diastolic wall shear stress and delayed onset of peak wall shear stress compared to healthy controls (P<0.001).
Case-Control (n=21)
Does 4D PC-MRI detect differences in wall shear stress and flow patterns in patients with ascending aortic dilatation compared to healthy controls?
4D PC-MRI demonstrates that ascending aortic dilatation is associated with altered wall shear stress and abnormal flow patterns, including increased diastolic WSS and vortical flow.
p-value: p=<0.001
PURPOSE: To estimate surface-based wall shear stress (WSS) and evaluate flow patterns in ascending aortic dilatation (AscAD) using a high-resolution, time-resolved, three-dimensional (3D), three-directional velocity encoded, radially undersampled phase contrast MR sequence (4D PC-MRI). MATERIALS AND METHODS: 4D PC-MRI was performed in 11 patients with AscAD (46.3 ± 22.0 years) and 10 healthy volunteers (32.9 ± 13.4 years) after written informed consent and institutional review board approval. Following manual vessel wall segmentation of the ascending aorta (MATLAB, The Mathworks, Natick, MA), a 3D surface was created using spline interpolation. Spatial WSS variation based on surface division in 12 segments and temporal variation were evaluated in AscAD and normal aortas. Visual analysis of flow patterns was performed based on streamlines and particle traces using EnSight (v9.0, CEI, Apex, NC). RESULTS: AscAD was associated with significantly increased diastolic WSS, decreased systolic to diastolic WSS ratio, and delayed onset of peak WSS (all P < 0.001). Temporally averaged WSS was increased and peak systolic WSS was decreased. The maximum WSS in AscAD was on the anterior wall of the ascending aorta. Vortical flow with highest velocities along the anterior wall and increased helical flow during diastole were observed in AscAD compared with controls. CONCLUSION: Changes in WSS in the ascending aorta of AscAD correspond to observed alterations in flow patterns compared to controls.
Bieging et al. (2011) conducted a case-control in Ascending aortic dilatation (n=21). 4D PC-MRI vs. Healthy volunteers was evaluated on Diastolic wall shear stress, systolic to diastolic WSS ratio, and onset of peak WSS (p=<0.001). Ascending aortic dilatation evaluated by 4D PC-MRI was associated with increased diastolic wall shear stress and delayed onset of peak wall shear stress compared to healthy controls (P<0.001).